The conventional preparation of fluoroorganic compounds involves the reaction of chloro-, bromo-, or iodoorganic compounds with ionic fluorides such as KF. Prior workers found that when crown ethers are used to chelate the potassium ion in such ionic fluorides, the fluoride reactivity is enhanced and yields of the corresponding organic fluorides are significantly increased.
KF is prepared from HF and HF is derived from fluorspar (calcium fluoride, CaF.sub.2). If CaF.sub.2 could be used directly as the fluoride source in such fluorination reactions, then the cost of preparing the fluoroorganic compounds could be reduced significantly. Unfortunately, CaF.sub.2 exists as a stable crystal with a high crystal lattice energy and is generally considered to be inert under most conditions other than that of high acidity and high temperature (above 300.degree. C.)
We considered the possibility that CaF.sub.2 might also be activated by crown ethers; however, our initial attempts to conduct fluorination reactions with CaF.sub.2 in the presence of crown ethers failed.
It is accordingly an object of this invention to provide a means of activating CaF.sub.2 sufficiently to serve as a fluorinating agent for the general preparation of fluoroorganic compounds from haloorganic starting materials in which at least one halo atom is replaceable with a fluorine atom by metathetical exchange.
Other objects and advantages of the invention will become apparent from the following description.